In a medium pot add water and rice and bring to a boil. Once boiling, cover pot with lid and reduce heat to low. Simmer on low for 30 minutes. Remove from heat and allow to rest with the lid on for 5 to 10 minutes.
In a small saucepan, add the rice vinegar and sugar. On medium heat, cook until sugar has dissolved. Remove from heat and set aside. Once rice is cooked, add rice vinegar mixture and mix well. Allow to completely cool. Rice should be sticky but not pasty.
In a medium baking pan, season chicken breast with salt and pepper. Cover chicken with plum sauce and 1 tbsp olive oil.
Peel sweet potato and cut lengthwise, into strips just under ½ inch thick. On a small baking sheet, place strips on parchment paper and drizzle with the remaining olive oil. Sprinkle with salt and pepper and place in oven.
Bake the chicken and sweet potato for 25-30 minutes or until the chicken is cooked through and the juices run clear and the sweet potato is tender. Remove from the oven and cool.
Slice chicken breast into thin strips and set aside.
Place plastic wrap on top of sushi rolling mat. Add nori sheet on top of plastic wrap. Dampen hands then pick up a handful of rice and spread it onto half of the nori sheet.
Place toppings along the middle of the rice. Hold the near edge of the mat, lift up and roll away from you. Wet the top of the nori that has no rice with water to help seal the roll. Once completely rolled, seal with the plastic wrap on each end of the roll and place in fridge to chill until firm. Alternatively, you can omit the plastic wrap and wrap after.
Cut rolls into rounds. Serve with wasabi, soy free soy sauce and sliced serrano peppers.